Pump



Feb- 25 1941 G. A. WAHLMARK 2,232,984'-A y f PUM P Filed sept; 8. 1938 s sheets-sheet :s

1N VENTOR.

Patented 1=b.2s,1941 l y 2,232,984

UNITEDI STATES PATENT yOFFICE A PUMP Gunnar A. Wahlmark,v Rockford, Ill. Applieation september s, 193s, serial No. 228.966

9 claims. (c1. 1oz- 173) The invention relates more particularly to a Another object is to provide. such aV pumping piston and cylinder type of pump, it being the mechanism with means for priming the iiuid general object of the invention to provide a new circuit to which the auxiliary cylinders are conand improved multi-piston pump. nected.

Another object of the invention is to provide Further objects will become readily' apparent 5 a pump embodying a plurality of pistons and from the following detailed description taken in cylinders actuated by a wobble plate device with connection with the accompanyingdrawings, new and improved means for moving the pistons wherein:

through their suction strokes. Fig. 1 is a longitudinal, horizontal central sec- Another object is to provide a pump having a tion through a preferred form of the invention. 10 plurality of piston andt cylinder devices actuated Fig. 2 is a fragmentary View along the line 2--2 by an' adjustable wobble plate together with of Fig, 1. fluid pressure operated means for returning the Fig. 3 is a fragmentary elevation partly in pistons through their suction strokes. section along the line 3-3 of Fig. 6.

In fluid pumps of the wobble plate type, the Fig. 4 is a transverse section approximately 15 pistons are generally returned through their along the line 4 4 of Fig.`1.

suction strokes by means of springs which main-v Fig. 5 is a transverse section approximately tain the outer ends of the pistons in engagealong the line 5-5 of Fig. 1. ment with a portion of the wobble plate or by Fig. 6 is a transverse section approximately means of connecting rods or links. Such devices along the line 6-6 of Fig. l. 20 are provided to insure the return of the pistons Fig. 7 is a fragmentary elevation similar to and permit the pump to suck fluid into the Fig. 3 of amodiedform of the invention. y cylinders during the return or suction strokes While my nVeIltOn iS susceptible of embodiof the pistons. Devices of this kind, however, ment in many dilerent forms, I have shown in have given considerable trouble. It is, therefore, the drawings and shall herein describe in detail 25 a more specific object of theinvention to elimone such embodiment and a modification thereof inate the need for such mechanical devices and with the understanding that the present disto provide a pump of this character with means closure is to be considered as an exemplication for subjecting the pistons to fluid to 4obtain a of the principles of the invention, and it is not total pressure against the piston on the return intended to -limit the invention to the embodi- 30 stroke sufficient to maintain the outer end of ments illustrated. The scope of the invention the piston in engagement with the wobble plate will be pointed out in the appended claims. device. Y As shown in the drawings, the invention is em- Another object is to provide a pump having a bodied n a Dump comprising a cup-Shaped CaS- .35 plurality of piston and cylinder devices and a .ing l0, a Cylindrical Cyllldlf block il positioned wobble plate mechanism with pistons having enin the casing and having a flange I2 abutting the larged portions formingI auxiliary pistons and Open end of the casing, a plate I3 positioned means for subjecting these auxiliary pistons to against the cylinder block and forming a cylinfiuid under pressure so as to effect the proper der head, an annular member I4 positioned return of the pistons during the operation of against the plate I3 and a closure member I5 40 the pump. abutting the annular member I4. The parts I2,

Another object is to` provide a pumping I3, I4, and I5 are preferably secured together by a mechanism having a plurality of main piston plurality of headed screws I2 (Figs. 4 and 5). and cylinder devices, auxiliary pistons and These same parts as a unit are secured to the cylinders associated one with each main piston, casing l0 by means' 0f a plurality Of annularly 45 uid conducting means 'interconnecting the spaced and headed screws I5 which pass through auxiliary cylinders to form a substantially closed bores in Said parts and into Screw-threaded fluid circuit so that uid forced out vof auxiliary sockets in the casing. A shaft I6 is rotatably cylinders during the pressure strokes of the mounted in the CSing by means of a pair of ball associated main pistons is transferred to other bearings I1 positioned ina recess I8 in the closed 50 auxiliary cylinders to act against the auxiliary end portion l0' 0f the Casing. arid a 1'01181F4 bea/rpistons therein and move the associated main ing I9 supported partly on the cylinder block Il pistons through their return or suction strokes, and partly on the plate I3. The shaft I6 carries and means for maintaining the auxiliary cylin a wobble plate device or mechanism 20 which is ders and the interconnecting means full of uid. arranged to actuate a plurality of pistons 2| 55 Cil which are slidably mounted in cylinders formed in part by bores 22 in the cylinder block and in part by recesses 23 in the plate I3. An inlet port 24 for the pump is formed in the closure member I and connects with an annular passage 25 in the closure, which in turn connects with a series of circumferentially spaced supply ports 26. An outlet port 21 in the closure member I5 connects with an arcuate discharge passage 28 which in turn communicates with a series of circumferentially spaced discharge ports 29. The discharge ports at their inner ends communicate with the outer portion of a cylindrical valve chamber 38 formedv within the annular member I4 and between the adjacent faces of the plate I3 and closure member I5. The inlet ports 26 communicate with the valve chamber at points spaced radially inwardly from the discharge ports, as shown in Fig. 1.y A valve 3| is operable in the chamber 30 and is arranged to connect the supply and discharge ports alternately with cylinder ports 32 which are formed in the -plate I3 and communicate with the recesses 23. These cylinder ports preferably terminate in rectangular openings which communicate with the chamber 30, as shown in Fig. 6, in order to obtain slow opening and closing of the ports when functioning as outlets, and rapid opening of the cylinder ports when functioning as inlets. 'I'his prevents the hammering action which otherwise occurs and causes noise due to the incomplete filling of the cylinders on the suction strokes.

The valve device 3| is herein shown in the form of a wheel (Figs. 1, 3 and 6) having-an outer rim 33 and an inner hub 34 which are connected by means of a web 35 provided with a plurality of apertures 36 (Fig. 6). .This valve device is mounted on an eccentric pin 31, formed on the adjacent end of the shaft I6, by means of a ball bearing 38 so that during operation of the shaft the valve device has an orbital movement whichv results in a sliding movement of the rim 33 across the cylinder ports 32 so as first to connect the cylinder ports to the supply ports 26 and alternately to the discharge ports 29. Both the rim 33 and the hub 34 of the valve device have a sliding fit against the adjacent surfaces of the plate I3 and closure member I5 so as to confine the inlet fluid within the annular space formed intermediate the rim 33 and hub 34 and to confine the discharge fluid Within the valve chamber 30 externally of the valve.

The construction and operation of the pump and its valve mechanism are more fully described and claimed in my copending application Serial No. 143,069, filed May 17, 193'?.

The wobbler mechanism 20 for actuating the pistons 2| through their pressure strokes is herein disclosed as comprising an annular member 40 having a pair of opposed flat surfaces 4I which nt against flat surfaces 42 formed on an enlarged portion 43 (Fig. 1) of the shaft I6. 'I'he annular member 4D is pivotally mounted on the shaft by means of a pin 44 extending through aligned bores in the member and shaft. The annular member 40 has an outwardly extending flange 46 against which one race 41 of a ball bearing 48 is positioned. The other race'49 of the ball bearing is provided with a flat surface 50 for engaging the adjacent rounded ends 5I of the pistons 2I. Preferably, the adjacent ends of the pistons 2I are provided by round headed inserts 54 which engage the adjacent flat surface 58 of the race 49 so as to provide a driving connection between the wobble plate and the pispin 69 (Figs. 1 and 4).

tons to actuate the pistons through their pressure strokes.

The wobble plate device is adjustable angularly about the pivot pin 44 for the purpose of adjusting the stroke of the pistons. As illustrated in the drawings, this adjusting means comprises an adjusting member which is slidable longitudinally 1ike a key in a recess or keyway 66 in the shaft I6 and has an inclined cam surface 61 which engages a follower on the wobble plate consisting of a roller 68 mounted on a shaft or It will be readily apparent from Fig. 1 that movement of the adjusting member 65 toward the right swings the wobble plate device in a counter-clockwise direction around the pivot pin 44 to lengthen the stroke of the pistons, and that movement of the adjusting member 65 in the opposite direction permits the wobble plate device to swing in a counterclockwise direction to shorten the stroke of the pistons. A coiled spring 60 is positioned partly ln a diametrical bore 6I in the shaft and engages the annular member 40 and urges Said member in a direction to maintain contact of the roller 68 with the cam 61.

'Ihe adjusting member 65 is movable longitudinally of the shaft by means including a ball bearing 10, the inner race 1I of which slides longitudinally on the shaft I6 and nts into a recess 12 in the member 65 and the outer race 13 of which is formed on a collar 14 which surrounds the shaft I6 and is slidably Vmounted in a bore 15 in the cylinder block II. A lever 16 has one end 11 inserted in an opening 18 in the collar 14 and is pivoted intermediate its ends by means of a bushing 19 secured in a tapered opening 89 in the cylinder block II. The other end of the lever 16 has an opening 8| therethrough provided with a spherically surfaced portion 82 in Which a ball- 83 is positioned. This ball has a screw-threaded bore 84 through which a screw vided with a squared end 88 to facilitate operation thereof by a suitable tool. 'I'he wobble plate and adjusting mechanism are similar to that disclosed in my copending application Serial No.

189,049, led February 7, 1938.

The invention provides a fluid operable means for actuating the pistons 2I through their return or suction strokes and for keeping the round surfaces 5I of the inserts 54 in contact with the race 49. In the form disclosed in the drawings, this means includes auxiliary piston and cylinder devices associated one with each of the main pistons. Thus, auxiliary cylinders 90 (Fig. l) are formed as enlarged portions of the bores 22 and auxiliary pistons 9I, in the form of enlarged portions of the pistons 2l, operate therein. The auxiliary cylinders 90 are interconnected by means of an annular passage 92, formed in the cylinder block II, and a plurality of ports 94 extending between the auxiliary cylinders 90 and the annular passage 92. The fluid circuit formed by the annular passage 92, ports 94, and auxiliary cylinders 90 is completely filled with fluid so that when some of the pistons are moving through their pressure strokes (toward the left in Fig. 1), the fluid displaced from the associated auxiliary cylinders flows through the corresponding ports 94 and through the passage 92 and through other ports 94 and -into the auxiliary cylinders of pistons moving through their suction strokes. Since for any given piston stroke the total volume of this circuit remains substantially constant, the uuid displaced by some of the auxiliary pistons serves'to actuate other auxiliary pistons.

In order to insure eiiicient operation of the pistons, means is provided for replenishing the fluid circuit with fluid for any which might leak out and at the same time maintain the fluid in the circuit under pressure so as to avoid any lost motion. This means is herein disclosed as comprising a passage for conducting iiuid from the lower pa'rt of the discharge portion of the valve chamber 30 to the fluid circuit, and a pump device in the passage operable to pump uid through the passage at times when the uid in the outlet passage is not under suflcient pressure. As shown in 3, the passage comprises (in order) a port 96, a bore 91 and a port 98 in the closure I5, a pump inlet port 99, a pump cylinder chamber |00 and a pump discharge port IOI in the annular member |4, a port |02 and a bore |03 in the plate I3, and a recess |04 and a port |05 in the cylinder block. 'Ihe port |05 communicates at its discharge end with one of ,the auxiliary cylinders 90. A check valve |06 is positioned in the recess |04 against the end of a bushing |01 which lines the bore |03 and functions to pass uid from the bore |03 and into the port |05 and to prevent reverse flow of fluid. This valve is normally held against the end of the bushing by means of 'acoiled spring |08 which is backed up by a flangedannular member |08 pressed onto the bushing.

A piston |09 is slidably mounted in the pump chamber |00 and has an integral rod ||0 which slides in a bushing tted into one end of the chamber |00. The inlet port 99 and outlet port |0I are so arranged that the inlet port closes rst during the pressure stroke and by reciprocating the piston I 09 fluid `is pumped into the port |03. As shown in Fig.. 3, the inlet port 99 is positioned rsomewhat below the outlet port |0| so that when the piston |09 is raised a quantity of :fluidv is trapped in the upper portion of the chamber |00 and forced out through the port |0I. The piston |09 is actuated through its suction strokes by a lever ||2 (Figs. 3 and 6) which is pivoted at one end by a pin |I3 and has its other end positioned in a peripheral groove ||4 in the rim 33 ofthe valve 3 I. Dueto the orbital movement of the valve caused by the eccentric driving pin 31, the lever ||2 is oscillated about the pin |I3, an intermediate portion I|5 of the lever engaging the piston rod I|0 and serving as an actuator for the return stroke. The piston |09 is moved through its pressure stroke by means of a coiled spring |I6 positioned in a housing II1 which is secured to the pump parts by screw devices II8. Preferably, a strainer 91' is positioned in the bore 91. A relief passage |34 is provided to prevent pressure from building up in the housing ||1.

In the modified form illustrated in Fig. 7, the modification resides in the specific form of the priming pump. As illustrated, a pump piston |20 is mounted in a cylinder I2| formed inthe annular member I4 and has a rod |22, the outer end of which is in direct engagement with the rim-33l of the vmain valve 3|. A bushing |23 surrounds the rod |22 and is secured in the cylinder I2I so as to close the upper end thereof. In this form of the invention, fluid is supplied to an inletk port |24 by means of a passage |25 which communicates at its other end with the 3 main pump discharge passage 28.` A discharge port |28 for the priming pump communicates with a port |21 corresponding to the port |02 of the form of the invention illustrated in Figs. 1 to 6. A check valve device I 28 is positioned intermediate the port |21 and a port |29 which communicates with one of the auxiliary-cylinders 90. The piston |20 -is operated through its lsuction stroke by means of the valve rim 33' and is operated through its of a coiled spring |30.

When the preferred form of the invention is installed and ready for operation, the shaft I6 is connected to a suitable prime mover, the inlet port 24 is connected to a fluid supply andthe outlet port 21 is connected to some form of load. The pump isV mounted by means of a flange |35 on the casing I0 in a position such that the priming pump chamber |00 is near the bottom of the pump, so that it will always ube supplied with pressure' stroke by means uid by gravity from the discharge side of the l valve 3| or the passage 20. Upon driving the shaft I6, the wobble plate then acts to move the pistons through their pressure strokes as the valve device 3| functions to control the inlet and outlet of fluid to and from the pump cylinders. In the event the fluid circuit, including the auxiliary cylinders, is filled with fluid, the pump immediately operates at whichever stroke has been previously selected by means of the adjusting member 65. In the event the fluid circuit is not filled and thereis no pressure in the discharge passage 28, the -piston |09 is operated and serves as a priming pump to pump fluid into the port |02, past the check Valve |06, and into the iiuid circuit. The priming piston |09 functions in this manner until the iiuid circuit is completely lled.

Although the invention is suitable for use in many different types of applications, a particularly important application is that of supplying fluid under pressure for actuating supports in machine tools. When the pump is embodied in a circuit with a suitable actuator', an

incompressible fluid, such as oil,` is generally used. Under these circumstances, the pressure developed by the pump depends upon the resistance encountered by the actuator of the hydraulic circuit. In the form 'of the invention illustrated, the coil spring II6 for actuating the primary pump piston |09 has been selected so as to force fluid at pressures up to 400 or 500 pounds per square inch through the outlet port |0I. The priming .pump continues to function as long as the pressure in the discharge passage 28 is less l than this amount. g `charge passage 28 exceeds this amount (the pres- When the pressure in the dissure in this passage frequently arising to 1,000 pounds, if necessary), the pressure on the upper side of piston |09 (Fig. 3) becomes sufliciently great to hold the piston |09 in its lowermost position against the action of the spring IIB. from the discharge passage 2B then iiows through the connecting passage to the fluid circuit under the discharge pressure of themain pump, and the priming pump piston is no longer actuated by the valve 3|.

In providing a fluid means for returning the pistons Aof the pump through their suction strokes, the invention has eliminatedthe need for springs, links, and other mechanical devices which cause trouble due to Wear and the attendant lost motion. Furthermore, the pistons during their return strokes are normally under the output pressure of the pump and, therefore,

there is a uniformly distributed pressure all around the surface of the ball bearing race 49 soas to provide a balanced load on the wobble plate. This form of means for returning the pistons also eliminates the need for any torque arm. The result is a pumping mechanism which operates smoothly and efficiently.

The cylinder ports 32, when provided with rectangular openings communicating with the valve chamber 30, are instrumental in reducing noise and providing smooth operation due to the fact that the slow opening and closing of these ports when functioning as outlets prevents the hammering action which usually occurs by the inrush of pressureA under fluid into the incompletely filled cylinders.

By locating the wobble plate adjusting member 65 on that portion of the shaft I6 which is surrounded by the cylinders and extending the operating lever 16 outwardly through an opening passing intermediate to adjacent cylinders, the overall length of the fluid pump is materially reduced, the control mechanism then lying within a portion of the device already occupied by the cylinders.

I claim as my invention:

1. A fluid pump comprising, in combination, a plurality of main piston and cylinder devices, means for controlling the flow of fluid into and out of the cylinders of said devices, means for actuating the pistons through their pressure strokes, means for returning the pistons through their suction strokes comprising auxiliary piston and cylinder devices associated one with each of said main piston and cylinder devices, fluid conducting means interconnecting the auxiliary bcylinders in a substantially closed circuit, and means for maintaining said auxiliary cylinders and circuit filled with fluid under pressure comprising an auxiliary pump and a passage connecting the outlet of said auxiliary pump with said circuit.

2. A fluid pump comprising, in combination, a plurality of main piston and cylinder devices, inlet and outlet ports, means for controlling the flow of fluid into and out of the cylinders of said devices, means for actuating the pistons through their pressure strokes, means for returning the pistons through their suction strokes comprising auxiliary piston and cylinder devices associated one with each of said main piston and cylinder devices, and means for maintaining fluid under pressure in said auxiliary cylinders comprising fluid conducting means between the voutlet of the pump and said auxiliary cylinders, a check valve operable to permit flow through said fluid conducting means to the auxiliary cylinders when the outlet pressure of the pump exceeds a predetermined value, and an auxiliary pump operable to force fluid through said fluid conductinig means and checkl valve when the outlet pressure of the pump is insufficient to operate the check valve.

the outlet of the pump and said auxiliary cylinders yand an auxiliary pump device operable to pump fluid through said fluid conducting means.

4. A fluid pump comprising, in combination, a plurality of main piston and cylinder devices, a drive shaft, means driven by said shaft for actuating said pistons through their pressure strokes, inlet and outlet ports, means for controlling the flow of fluid into and out of said cylinders, means for returning the pistons through their suction strokes comprising auxiliary piston and cylinder devices associated one with each of said main piston and cylinder devices, fluid conducting means interconnecting the auxiliary cylinders in a substantially closed circuit, means for maintaining said auxiliary cylinders and circuitfllled with fluid under pressure comprising a passage connecting said circuit with the outlet for the pump, a check valve in said passage for preventing return flow therethrough, and a pumping device in said passage intermediate the pump outlet and said check valve having a piston and cylinder, means operated by said drive shaft for actuating said last mentioned piston through its suction strokes, and spring means for'actuating said last mentioned piston through its pressure strokes.

5. A fluid handling device comprising, in combination, a casing, a drive shaft rotatably mounted thereon, a plurality of parallel cylinders arranged annularly about a portion of said s'haft, pistons in said cylinders, means for controlling the flow of fluid to and from the cylinders, an angularly adjustable wobble plate carried on said shaft, and means for adjusting said wobble plate' comprising a longitudinally movable element slidably mounted on and rotatable with the portion of said shaft surrounded by said cylinders,

a collar surrounding said shaft, a ball bearing connecting said collar to said element and an operating member connected at one end to said collar and extending substantially radially outwardly through an opening in the casing passing intermediate two adjacent cylinders.

6. A fluid pump comprising, in combination,

a casing, a shaft rotatably mounted in the casing, a plurality of rnain piston and cylinder devices, inlet and outlet ports, means for controlling the flow of fluid into and out of the cylinders of said devices including a wheel-like valve and eccentric means on said shaft for actuating said valve, means driven by said shaft for actuating the pistons through their pressure strokes, means for returning the pistons through their suction strokes comprising auxiliarypiston and cylinder devices associated one with each of said main piston and cylinder devices, and means for maintaining fiuid under pressure in said auxiliary cylinders comprising means interconnecting the auxiliary cylinders in a substantially closed circuit, a fluid passage between the outlet of the pump and said circuit, an auxiliary pump device operable to pump fluid through said passage comprising a piston and a cylinder, means actu- 'ated by the rim of said wheel for moving the auxiliary piston through its suction strokes, and spring means for actuating said piston through its pressure strokes.

7. A fluid pump comprising, in combination, a casing, a shaft rotatably mounted in the casing, a plurality of main piston and cylinder devices, inlet and outlet ports, means for controlling the flow of fluid into and out of the cylinders of said devices including a wheel-like valve and eccentric means on said shaft `for actuating said valve,

means driven by said shaft for actuating the pistons through their pressure strokes, means for returning the pistons through their suction strokes comprising auxiliary piston and cylinder devices associated one with each of said main piston and cylinder devices, and means for maintaining fluld under pressure in said auxiliary cylinders comprising means interconnecting the auxiliary cylinders in a substantially closed circuit, a iluid passage between the outlet of the pump and said circuit, an auxiliary pump device operable to pump fluid throughsaid passage cornprising a piston and cylinder, means actuated by the rim of said wheel for moving the auxiliary piston throughits suction strokes, said means including an arm pivoted at one end on said casing and having its free end engaging the rim of said-wheel so as to be oscillated thereby and means on the intermediate portion of said arm for operating said piston, and spring means for actuating said piston through its pressure strokes.

8. A iiuid pump comprising, in combination, a casing, a shaft rotatably mounted in the casing, a plurality of main piston and cylinder devices, inlet and outlet ports, means for controlling the Yflow of fluid into and out of the cylinders of said devices including a wheel-like valve and eccentric means on said shaft for actuating said valve, means driven by said shaft for actuating the pistons through their pressure strokes, means for returning the pistons through their suction strokes comprising auxiliary piston and cylinder devices associated one with each of a casing, a shaft rotatably mounted in the casing, a plurality of main piston and cylinder de vices, inlet and outlet ports, means for controlling the flow of fluid into and out of the cylinders of said devices including a wheellike valve and eccentric means on said shaft for actuating said valve, means driven by said shaft for actuating the pistons through their pressure strokes, means for returning the pistons through their suction strokes comprising auxiliary piston and cylinder devices associated one with each of said main piston and cylinder devices, and means for maintaining iiuid under pressure in said auxiliary cylinders comprising means interconnecting the auxiliarycylinders. in a substantially closed circuit, a fluid passage between the outlet of the pump and said circuitan auxiliary pump device operable to pump fluid through said passage comprising a piston and cylinder, -and means including the rim of said wheel-like valve for actuating the piston of said auxiliary pump device.

GUNNAR A. WAHLMARK; 

